Impact-crusher for comminuting hard materials



Dec. 28, 1937f B GRAEMIGER HAL 2,103,454

IMPACT CRUSHER FOR COMMINUTING HARD MATERIALS Filed Sept. 13, 1934 Patented Dec. 28, 1937 W&CTCRUSHER FOR COMMINUTBVG HARD MATERIALS Benjamin Graemiger. Zolllkom and Werner Ludin, Winterthur, Switzerland, assignors to Hephaest A.-G. fiir motorische Krafterzeugung, Zurich, Switzerland, a corporation of Switzerland pp ication September 13, 1934, Serial No. 743,880

In Germany September 18, 1933 9 Claims. (01. 83-46) The present invention relates to an; impactcrusher for comminuting hard material, for instance coal to coal dust adapted to be used for coal-dust-firing of boilers and so on.

Impact-crushers are known in which the material to be pulverized is fed to the operative parts by a jet of compressed air, steam or gas. An automatic feed control is obtained by the eflect of the circulating material which, after partial pulverization does not pass the separators or the like, but falls back and is deposited onthe coarse raw material thereby retarding the feed of said coarse material which percolates the layer of raw material to be caught again by the jet of 15 air or gas to be projected anew on to the crushing body.

Experience shows that the automatic feed control is not reliable if the raw material to be comminuted is already comparatively fine. The cir- 20 culating material cannot percolate the raw mate'- rial and cannot pass on to the jet, the latter feeding therefore only raw material. The deposit of circulating material increases; the working of the separator etc., is finally affected thereby and 25 dust too coarse is produced. Some success in automatically controlling the input has been attained by adjusting the mixing tube-orifices or by regulating the feed in the entrance socket say by means of studs obstructing the flow of the raw 30 material, but such emergency devices proved unsatisfactory as the rate of flow of the raw material alters continuously with its moisture contents. Such charmes in the moisture and therefore in the rate of feed occur even in different 35 layers of one and the same bunker of raw material. It is quite impossible to provide devices which control automatically and effectively the feed under varying conditions, to prevent an overflow or to obviate the idle running of the 40 crusher.

The main object of the invention is to provide improved means tovcontrol the feed of raw material to the impact-crusher automatically and eil'ectively even under the very worstponditlons.

Another object of the invention is to prevent the idle running of the impact-crusher and to obviate at the same time the flooding of the same if the conditions improve.

To attain these and other objects, we provide an 50 impact crusher having ducts or the like by which at least a part of the circulating material falling back from the separator is separately led back to the jet which projects the raw material to be .comminuted by impact. v r

55 "According to our invention at least apart of the circulating material is brought back to the acting jet quite independently oi. the amount and of the condition of the raw material to be projected by the jet, and "also independently of the moisture content'and the coarseness of the raw material.

In a preferred construction of the new impactcmsher we pass at least part of the circulating material rejected by the separator separately to thegas jet when it leaves the expansion-nozzle. 10 By this arrangement the gas jet is loaded by the circulating material as soon as it leaves the expansion nozzle, thereby regulating its capacity to accept other raw material according to the amount of circulating material. The raw material to be fed to the jet may be stored in a central space surrounded by an outer space which is used to pass on all or part of the circulating material to the gas let. A division wall between the inner space for storing the'raw material and the outer chamber for the circulating material may be shaped to sense as part of the mixing tube. For instance, it may be shaped to form anozzle. The mixing tube may be subdivided in such a manner that one of the subdivisions receives raw material and the other circulating material. The circulating material passes unimpeded through the raw material to the second part of the acting gas jet. The circulating material influences the inflow of raw material owing to its eflect on the gas jet.

It has been ascertained that the raw material is being introduced into the mixing tube by being drawn round the inflow-edge oi. the mixing tube. A great influence is to be attributed to the air in the interstices of the loosely heaped raw material. If there is a large amount chair the inflow of raw material is facilitated by the suction action of the gas let. An interconnection by a duct or the like between the space in which the cir- 'culating material is deposited and the zone in which the inflow of the raw materialinto the mixing tube is ellected may have a controlling influence in a double sense: as long as the layer of deposited circulating material does not reach the entranceoriflce of such a duct only air will I pass therethrough, which facilitates the inflow of raw material into the. mixing tube. If on the contrary the layer of deposited circulating material reaches the entrance of said duct, the amount of air passingv therethrough is reduced and the inflow of circulating material increased. More circulating material is being led into the mixing tube and less-raw material. The circulating material i'alling-baclrzpreaents the inflow of raw mate-= material which automatically sets in has a controlling effect.

The duct may be used as an additional controlling device which may be brought to action when the mixing tube is subdivided.

In the drawing we have shown several embodiments 01 our invention.

Fig. 1 shows in sectional elevation in a diagrammatical manner an impact-crusher in which the raw material is arranged in a central space surrounded by a space to receive the circulating material.

Fig. 2 shows in sectional elevation part of another impact crusher in which the heavier circulating material is returned to a duct having the shape of a funnel surrounding the mixing tube.

Fig. 3 shows in sectional elevation in a diagrammatical manner an impact-crusher in which the circulating material passes at least partly through the raw material by returning to the acting jet, separate controlling means being shown to interconnect the collecting space of the circulating material with the inflow of the mixing tube.

Figs. 4 and 5 show in a diagrammatical manner and in sectional elevation part of an impactcrusher with different forms of return ducts for the circulating material.

All the impact-crushers shown in the drawing comprise a casing I, an expansion nozzle attached to the supply pipes for compressed fluid, such as air, gas and so on. All crushers shown comprise further an inflow I for the raw material and a mixing tube 4 through which the compressed fluid and the material to be comminuted pass, an impact body 5 against which the raw material to be pulverized is thrown, a separator l, and an outflow socket 8 for the discharge of the compressed fluid loaded by the pulverized material. Hie filter or separator l is provided with a number of slots 9 which interconnect the space above the separator 1 and the space below the same. Within the casing I, in the form shown in Fig. 1, a substantially conical division wall I5 is arranged which is adapted to receive the raw material being fed by the inflow 3. The space H within the wall I! is filled with raw material. The annular space is between the wall i5 and the casing l is adapted to receive the circulating material, that is such material which cannot pass the separator I and which is guided back by the vanes 6. Within the wall i5 at the lowest point thereof, a tubular part i6 is arranged which runs concentrically to the nozzle 2. The said part i6 may be shaped to form a nozzle. Moreover it :lorms part of the mixing tube 4 which is arranged within the space l4 concentrically to the nozzle 2. Between the parts 4 and it there is an annular opening through which raw material may pass from the space M to the jet or air expanding in the nozzle 2. Moreover an annular open space is provided between the parts 2 and i6 through which annular opening circulating material may enter the jet of gas passing through the mixing tube 4 on to the impact body. The device works as follows:

The compressed air or gas or steam expands in the nozzle 2 and projects the raw material and the circulating material through the mixing tube 4. The raw material is crushed by impact on the body 5, but some pulverizing of the raw material already takes place within the mixing tube 4, owing to the friction and the impact of the partirial and the back flow of additional circulatingcles of the raw material and the circulating material on each other. Some very coarse particles are thrown back by the body 5. Smaller particles are brought by the air stream along the vanes 6 to the separator 'l. The vanes are set oblique, so as to give the stream of air a certain rotational movement. Such particles too coarse to pass the separator are led back into the space I 3 as shown by arrow 30. Within the separator a second filtering action takes place and particles not having passed the finer meshes return by the slots 9. passes to the space I! and from said space I! through the annular slot into the jet, passing through the nozzle 2. The jet of expanded air takes moreover additional raw material from the space l4. The raw material is fed through the inflow socket 3, according to the amount of pulverized material passing through the outflow I. The angle at which the socket 3 stands agrees with the kind and the. coarseness of the raw material to be treated.

Part of the circulating material which is deposited on the raw material in the space l4 percolates the said material and passes mixed with the raw material proper on to the open slot between the parts 4 and I6, where it is taken off by the jet. If circulating material is deposited in the space M in excess to its capacity it flows over into the space i3 as shown by'arrow 3|. Practical results have shown that the greater part of the circulating material passes along the inner wall of the casing i into the space IS. The mixing tube 4 may be mounted adjustably in axial direction. By altering the position of the mixing tube the slot by which the raw material enters the jet of expanded air is widened or narrowed and more or less raw material may be caught by the air jet while the inflow of circulating material is not altered at all. The feeding of the material in equal amounts along the whole circumference of the jet vwill give a very high efficiency to the air jet.

The impact pulverizer as shown in Fig. 2 comprises a central division wall II which is pro-j tube 4, an annular slot being left between the parts 4 and II by which circulating material may pass into the opening between the nozzle 2 and the mixing tube 4. The raw material is led through the chute 3. It spreads around the said flange portion of the division wall II in such a manner that raw material is fed into the jet equally from all sides. Circulating material may pass through the opening I! into the raw material space and is deposited on the raw ma-- terial therein. The mixing tube may be mounted adjustably in its axial direction in order to vary the widthof the annular entrance slots for the raw material to be projected.

The construction of the device shown in Fig. 3 difiers from that shown in Fig. 1 in that the division wall I5 is done away with and circulating material, that is all the particles which have been rejected by the separator l. 5 are deposited on the top of the raw material flowing in by the socket 3. At least one pipe I0 is provided, the lower end of which is adjacent the lower face of the mixing tube 4. The upper end of the pipe ll projects a certain amount above the level of the raw material within the casing i. The

jet of expanded air ejected by the nozzle 2 sucks air through pipe ill. The air sucked in by the Most of the circulating material the inflow of raw material into the jet will'be less. Moreover circulating material is taken up by the jet in an increasing manner. An automatic control of the material projected against the impact body 5 is attained thereby. If the amount of circulating material is increased the inflow oi raw material is decreased and so on. The pipe III might be shaped in any suitable manner. It may have the shape of a funnel and actsimilarly to the part II described with reference to Fig. 2.

The construction ofthe device shown in Fig. 4 is similar to that shown in Fig. 1. On the mixing-tube an outer concentric mantle I1 is arranged. With the space ll of annular crosssection communicate two pipes I 9. The upper free ends of the pipes Illare at a certain distance Irom the wall I and outside, the upper edge of the division wall II. The lower end of the outer wall I1 ends just above the lower face of the mixing tube 4. A jet issuing from the nozzle 2 sucks air through the pipes II. The deposit of. circulating material may grow so far that such circulating material is sucked in by the pipes l9. The controlling action of 'the said circulating raw material is the, same as described with reference to the'pipe It of Fig. 3.

The device shown in Fig. 5 comprises within the casing I asecond cup-shaped container is in. which the circulating material is collected. Between the parts I and 24 a space 23 is left iormingfa duct through which circulating material 22 flows downwardly as'soon as material in the-container 24 overflows. The container 26 is provided at its lower end with an opening arranged cbncentric to the nozzle? and the mixing tube l p lfbiectinginto the said container 25. The partitIom-wall 2-5 is provided with an opening wiiich-ioi'mstogether with the wall of the containerlliand-thecasing I a duct 23. The duct 28 iormsjan annular orifice concentric to the circular flange 21.. of the container 14. The Jet issued'byi the nozzle 2 has*a sucl:ing efiect and draws air from the space above the mixing tube I. The air drawn in loosens the particles of the raw.material 28 and facilitates their flow into the "jet. As soon as the container 24 is full the excess of the circulating material 22 flows in the direction of the arrow to the duct 23 downwardly and enters the let. Also raw material 2| will now enter the jet. The controlling action of the circulating material comes now again in force as described with reference to Figs. 3 and 4. an annular ring may be arranged above the upper orifice of duct 22 to lead the circulating material into the container 26.

Extensive trials have proved the efllciency of such an automatic controlling device. Comminuting devices of the type described show the most uniform working. The supply of the mixture of air and the pulverized material may be graded by adjusting the separator within very wide limits. 11 the separator is set once the mixture is uniform. under any condition.

It will be understood that in practice various changes in the form, proportion and the minor comminuted, a

out departing from the spirit or sacrificing any of the advantages of the invention. For instance,

other separating devices may be combined with the comminuting device. the ducts may be arranged outside the casing I and the means to introduce the circulating material into the jet may be placed in the centre of the nozzle 2 near the narrowest cross-section thereof. The circulating material may be introduced coaxially to the expansion nozzle 2. The inflow of raw material may be effected from 2 or 3 diiferent bunkers, and so on.

Having describedour invention, what we claim 1. A comminuting device comprisi a casin adapted to receive a bed of raw ma t rial to b: feed inlet for said raw material. a nozzle for forcing a stream of gas at high velocity into said casing and in contact with said raw material to entrain the particles of said material, means in said casing for separating the finer from the coarser and heavier entrainedparticles, an outlet for conducting the finer material entrained in said gas from said casing, and a passage extending from a section slightly above the bed of raw material to a section adjacent to the outlet of said nozzle for conducting at least a portion of said separated coarser particles separate from said raw material and to a point adjacgeng to the outlet of said nozzle.

comminuting device, includin a c 1 having an inlet for raw material to be pulvel i zifd an expansion nozzle having aninlet for a gaseous fluid under pressure, a mixing tube having its inlet spaced from the outlet of said nozzle and below the normal level 01' the raw material in said casing, whereby said raw material may enter said jet and be delivered thereby through said mixing tube, an impact body, a separator, and means for conducting coarse particles rejected by the separator to a point between the outlet oi said nozzle and the inlet 01' said mixing tube independently of the down flow of the raw material, for reintroduction into the jet. I

3. A comminuting device, including a casing having an inlet for raw material to be pulverized. an expansion nozzle having aniinlet for a gaseous fluid under pressure, a mixing tube having its inlet spaced from the outlet of said nozzle and below the normal level of the raw material in said casing whereby said raw material may enter said Jet and be delivered thereby through said mixing tube, an impact body, a separator, a compartment within said casing for receiving coarse particles rejected by the separator, and an opening leading from said compartment for delivering said coarse particles between the outlet 01 said nozzle and the inlet of said mixing tube separate from and on oi contact with the raw material.

4. A comminuting device as defined in claim 3 in which the compartment encircles the raw material in the casing, and said compartment has a delivery opening concentric "with the nozzle orifice.

5. A comminuting device, including a casing having an inlet for raw material to be pulverized, an expansion nozzle having an inlet for a gaseous fluid under pressure. a'inixlns tube havingits inlet spaced from the outlet of said nozzle and below the normal level Of-"the raw material in said casing, whereby said raw material may enter said jet and be delivered thereby through said mixing tube, an impact body, and a separator, said casing having separate compartments i'or the raw material and the coarse particles rejected by said separator, said compartments having separate outlet openings directly leading into the space between the outlet of the nozzle and the inlet of the mixing tube.

6. A comminuting device, including a casing having an inlet to!" raw materiel to he pulverized an expansion nozzle having an inlet for a gaseous fluid under pressure, a mixing tube having its inlet spacedfroin the outlet of said nozzle and below the normal level of the raw material in said casing, whereby said raw material may enter said jet and he delivered thereby through said mixing tube, an impact body. and a separator, said casing having a partition wail provided with an opening concentric with and disposed between the outlet oi the nozzle and the inlet 0! the mixing tube, whereby said raw material and said coarse particles may separately enter the jet at spaced points along the length of the latter.

'1. A ccmminuting device as defined in claim 5, in which the opening in said partition wall is in the form ot a tubular conduit section.

ii. A comminuting device as defined in claim 2, in which the conducting means includes a con duit leading from above the raw material through the latter to a point adjacent to the inlet of the mixing tube.

9. A comminuting device including a. casing adapted to receive raw material to be comminuted, a nozzle for directing a stream of fluid under pressure at high velocity into said casing, a mixing tube having an inlet spaced from the outlet of said nozzle and disposed below the normal level of the raw material in the casing whereby said raw material may be entrained in the jet deiivered from the nozzle to the mixing tube, an impact hody in said casing, and means in said casing for receiving coarser and heavier particles delivered with the fluid from said impact body and returning them to the jet at a point between the outlet oi the nozzle and the inlet of the mixing tube and independently of the downiiow of the raw material, whereby said coarser particles are entrained by the jet, and the capacity of said jet for entraining raw material will vary with the amount of said separated coarser particles returned to it. I

BENJAMIN GRAEMIGER. WERNER LUDIN. 

